What is @aws-sdk/smithy-client?
@aws-sdk/smithy-client is a foundational package used in the AWS SDK for JavaScript. It provides the core client and command abstractions that are used to build service clients for AWS services. This package is part of the modular AWS SDK for JavaScript (v3), which allows developers to import only the specific AWS services they need.
What are @aws-sdk/smithy-client's main functionalities?
Client Creation
This feature allows you to create a custom client by extending the base Client class provided by the @aws-sdk/smithy-client package. This is useful for creating service-specific clients.
const { Client } = require('@aws-sdk/smithy-client');
class MyServiceClient extends Client {
constructor(config) {
super(config);
}
}
const client = new MyServiceClient({ region: 'us-west-2' });
Command Creation
This feature allows you to create custom commands by extending the base Command class. Commands encapsulate the input and middleware logic for making API calls.
const { Command } = require('@aws-sdk/smithy-client');
class MyCommand extends Command {
constructor(input) {
super();
this.input = input;
}
resolveMiddleware(clientStack, configuration, options) {
// Middleware logic here
}
}
const command = new MyCommand({ key: 'value' });
Middleware Stack
This feature allows you to create and manage a stack of middleware functions that can be used to modify the behavior of commands and clients. Middleware can be added at various stages of the request lifecycle.
const { MiddlewareStack } = require('@aws-sdk/smithy-client');
const stack = new MiddlewareStack();
stack.add((next, context) => async (args) => {
console.log('Before request');
const result = await next(args);
console.log('After request');
return result;
}, {
step: 'initialize',
name: 'loggingMiddleware',
});
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